1. Field of the Invention
This invention relates to an ink jet recording apparatus for recording on a recording medium by discharging ink from recording means.
2. Related Background Art
A recording apparatus having a printer, a copying machine, a facsimile equipment, or other functions provided therefor, or a recording apparatus used as an output equipment for a complex machine or a work station including a computer, a wordprocessor, or the like is structured to perform recording images (including characters, symbols, and others) on a recording material (recording medium) such as a sheet, a thin plastic sheet (for use of an OHP or the like) in accordance with the respective image information. Then, depending on the methods of adopted recording means, recording apparatuses can be divided into an ink jet, a wire-dot, a thermo-sensitive, a thermal transfer, a laser beam, and some other types.
In a recording apparatus of a serial type using a method which performs its main scan in the direction intersecting the direction (subscan direction) in which a recording medium is carried, images (including characters, symbols, and others) are recorded by recording means (a recording head) mounted on a carriage which travels along the recording medium after the recording medium is set in a given recording position. After a recording is completed on one-line portion, a sheet feeding (subscan) is performed for a given amount. Subsequently, the image on the next line portion is recorded (main scanned). These operations are repeated in order to record images on a desired area of the recording medium. On the other hand, in a recording apparatus of a line type which records only by the subscan in the feeding direction of the recording medium, images are recorded on the entire area thereof in such a manner that the recording medium is set in a given recording position, and then, a sheet feeding (pitch feed) is performed for a given amount while continuously making the recording on one-line portion collectively.
Of these methods, the ink jet type (ink jet recording apparatus) is to record by discharging ink from recording means (recording head) onto a recording medium, and makes it easier to arrange the recording means compactly for recording images at a high speed in a high precision. Further, with this type, a recording is possible on an ordinary paper without any special treatment. The operation is possible at a lower running cost accordingly. Also, being of a non-impact type, this method produces lesser noises. Among other advantages, it is also easier for this method to use ink of many different colors for recording color images. Particularly, for a line type recording apparatus using a line type recording means wherein many discharge ports are arranged in the width direction of a recording sheet, it is possible to perform a recording at a higher speed.
Also, among the recording means (recording heads) of an ink jet type, particularly the one which utilizes thermal energy for discharging ink enables its recording means to be fabricated still more compactly because it is possible to easily prepare its recording head with highly densified liquid passages (discharge ports) arranged in it by forming electrothermal transducers, electrodes, walls of liquid paths, ceiling board, and the like by a film formation on a base board which processed by the application of an etching, deposition, sputtering, and other semi-conductor fabrication methods. Also, by utilizing the advantages provided by IC technologies and microprocessing techniques, an elongation and surface (two-dimensional) arrangement can be easily made for recording means of this type, hence facilitating the provision of a fully multiple means for recording as well as its highly densified assembly.
Now, in the aforesaid ink jet recording apparatus wherein ink is discharged from the discharge ports onto a recording medium for recording, ink tends to adhere to the ink discharge surface of such recording head due to ink mist generated at the time of ink discharge or ink splash or the like resulting from the impact when the discharged ink arrives at the recording medium. If ink adheres to a discharge port surface of the kind, it may clog the discharge ports or cause defective ink discharges. Therefore, in consideration of such problems, a structure has been arranged conventionally to remove the ink which has adhered to the circumference of the discharge ports by wiping it with a blade made of rubber or rubbery elastic material while allowing the recording head to move in a state that this blade is in contact with the discharge port surface of the recording head.
In other words, the recording head is mounted on the carriage which is shiftable in the direction almost intersecting t he feeding direction of the recording medium, and then, the recording head is allowed to travel together with the carriage so as to traverse the blade which is positioned in a sliding area of the carriage other than the printing area, hence cleaning the discharge port surface of the recording head by use of the blade thus arranged. In this case, the blade is usually positioned on the end portion of the carriage sliding area in order to make the apparatus smaller. Therefore, the recording head moves in the direction parting from the recording medium while being in contact with the blade.
However, according to a method of the kind to clean the recording head, vibration is inevitably generated at the leading end of the blade because of its elasticity the moment the blade parts from the recording head after the wiping operation has been carried out. As a result, there occurs a drawback that the ink which is transported (transferred) to the blade is caused by such vibration splash over the recording medium. Further, the ink splashed over the recording medium is accumulated on the control board in the recording apparatus, resulting in the possible generation of hindrance such as short circuit. Therefore, to counteract this, it is necessary to adhesively bond an ink absorbent or take some other measures in a location where the ink splash may take place.
Here, in order to eliminate the vibration of the blade, a structure is proposed in Japanese Patent Laid-Open Application No. 62-99153 to make it possible to change the configuration of the discharge port surface of a recording head smoothly (to enable it to present a U-letter shape) in the direction in which the blade shifts relatively. With this structure, the displacement amount of the blade is reduced along with its relative shifting because the discharge port surface changes its configuration smoothly in the direction in which the blade shifts relatively. In this way, it is arranged to reduce the vibration of the blade. However, for the provision of this structure, it is necessary to process the discharge port surface of a recording head which is an extremely sensitive part in terms of precision. Hence there is a possibility that because of this extra process, the arrangement precision of the discharge ports, and the distance between the discharge ports and energy generating elements are caused to vary. Consequently, it becomes difficult to maintain a high rate of yield when recording heads are fabricated. Also, being extremely difficult to eliminate the vibration of the blade completely, if a highly elastic material is used for a blade while a recording head is kept traveling at a high speed, ink splashes on the recording medium eventually.